The company wants to overcome the fear of pushing "the big blue button"

Ever looked at an app and decided not to try it because you didn't want to share your data? Facebook is trying to remove that stumbling block with a new service called anonymous log-ins that was announced Wednesday.

The idea is to let users log into apps and try them out without having to worry about who they're their sharing data with, and about whether the app will spam their friends with posts about their app use.

It's one of the ways Facebook is trying to overcome people's fear of pushing "the big blue button," as CEO Mark Zuckerberg put it at the Facebook's F8 developer conference in San Francisco.

That's the button that lots of developers use to let you log into their app using Facebook, and it's been holding some people back. "By giving people more control, they'll trust the app more," Zuckerberg said.

Facebook will still create an "anonymous identifier" that allows the app to recognize people across different devices, he said. And the hope is that people will sign in with their real identity later if they want to.

The change is a recognition that people are still uneasy about the data they share with Facebook and with mobile apps. The company needs to overcome those fears if it's to keep expanding the use of its services.

In the same vein, when people do decide to log into an app with their real identity, they'll get more granular control over what they share. They'll have to share their public Facebook profile, but they'll be able to choose not to share other information like their friends list, email, birthday, and their likes.

F8 is a conference for developers and we're not expected to hear about any big new Facebook features. Instead, the company is talking about new features in Parse, a service it bought last year that lets developers build mobile apps.

Zuckerberg also announced a "two-year stability guarantee" for developers who use the Facebook APIs, including for logging in and sharing. "Even if we change these cores APIs, we'll still keep supporting them for at least two years and maybe longer," he said.

It's also introducing API "versioning" -- every API it releases will have a version number, and developers will be able to choose which version they use. It also pledged to fix all major bugs in its development tools and APIs within 48 hours.

"We're focused on building a stable mobile platform," Zuckerberg said several times, a theme that's likely to be repeated throughout the day.

The new anonymous mode for logging into Facebook apps

James Niccolai covers data centers and general technology news for IDG News Service. Follow James on Twitter at @jniccolai. James's e-mail address is james_niccolai@idg.com